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From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
Date:   Thu, 27 Jan 2022 10:21:35 +0800
Message-ID: <CAAd53p7H3RApEHOzJYorD9VBnaPqYRkzE2g+8hAUXRToc=jbGg@mail.gmail.com>
Subject: Re: [PATCH 1/2] PCI/AER: Disable AER when link is in L2/L3 ready, L2
 and L3 state
To:     Mika Westerberg <mika.westerberg@linux.intel.com>
Cc:     bhelgaas@google.com, koba.ko@canonical.com,
        Russell Currey <ruscur@russell.cc>,
        "Oliver O'Halloran" <oohall@gmail.com>,
        Lalithambika Krishnakumar <lalithambika.krishnakumar@intel.com>,
        Joerg Roedel <jroedel@suse.de>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        linuxppc-dev@lists.ozlabs.org, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Wed, Jan 26, 2022 at 7:03 PM Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
>
> Hi,
>
> On Wed, Jan 26, 2022 at 03:18:51PM +0800, Kai-Heng Feng wrote:
> > Commit 50310600ebda ("iommu/vt-d: Enable PCI ACS for platform opt in
> > hint") enables ACS, and some platforms lose its NVMe after resume from
> > S3:
> > [   50.947816] pcieport 0000:00:1b.0: DPC: containment event, status:0x1f01 source:0x0000
> > [   50.947817] pcieport 0000:00:1b.0: DPC: unmasked uncorrectable error detected
> > [   50.947829] pcieport 0000:00:1b.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Receiver ID)
> > [   50.947830] pcieport 0000:00:1b.0:   device [8086:06ac] error status/mask=00200000/00010000
> > [   50.947831] pcieport 0000:00:1b.0:    [21] ACSViol                (First)
> > [   50.947841] pcieport 0000:00:1b.0: AER: broadcast error_detected message
> > [   50.947843] nvme nvme0: frozen state error detected, reset controller
> >
> > It happens right after ACS gets enabled during resume.
>
> Is this really because of the above commit of due the fact that AER
> "service" never implemented the PM hooks in the first place ;-)

From what I can understand, all services other than PME should be
disabled during suspend.

For example, should we convert commit a697f072f5da8 ("PCI: Disable PTM
during suspend to save power") to PM hooks in PTM service?

> >
> > There's another case, when Thunderbolt reaches D3cold:
> > [   30.100211] pcieport 0000:00:1d.0: AER: Uncorrected (Non-Fatal) error received: 0000:00:1d.0
> > [   30.100251] pcieport 0000:00:1d.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Requester ID)
> > [   30.100256] pcieport 0000:00:1d.0:   device [8086:7ab0] error status/mask=00100000/00004000
> > [   30.100262] pcieport 0000:00:1d.0:    [20] UnsupReq               (First)
> > [   30.100267] pcieport 0000:00:1d.0: AER:   TLP Header: 34000000 08000052 00000000 00000000
> > [   30.100372] thunderbolt 0000:0a:00.0: AER: can't recover (no error_detected callback)
> > [   30.100401] xhci_hcd 0000:3e:00.0: AER: can't recover (no error_detected callback)
> > [   30.100427] pcieport 0000:00:1d.0: AER: device recovery failed
> >
> > Since PCIe spec "5.2 Link State Power Management" states that TLP and DLLP
> > transmission is disabled for a Link in L2/L3 Ready (D3hot), L2 (D3cold with aux
> > power) and L3 (D3cold), so disable AER to avoid the noises from turning power
> > rails on/off.
>
> I think more accurate here is to say when the topology behind the root
> port enters low power states. Reason here is that you can't really tell
> from the OS standpoint whether the link went into L1 or L2/3 before the
> ACPI power resource is turned off.

OK, let me change the commit message a bit. My intention is to state
"transmission is disabled" in those Link states.

Kai-Heng

>
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=209149
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215453
> > Fixes: 50310600ebda ("iommu/vt-d: Enable PCI ACS for platform opt in hint")
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
>
> Thanks for fixing this!
>
> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>